EP0162896A1

EP0162896A1 - Multiple allergen-bearing matrixes useful for qualitative allergy screening

Info

Publication number: EP0162896A1
Application number: EP84904289A
Authority: EP
Inventors: Anne Beatrice Jepson
Original assignee: Ventrex Laboratories Inc
Current assignee: Ventrex Laboratories Inc
Priority date: 1983-11-10
Filing date: 1984-11-09
Publication date: 1985-12-04
Also published as: WO1985002262A1; AU3616684A; ZA848820B

Abstract

Dispositif de tamisage allergosorbant permettant un titrage qualitatif des sérums humains pour une hypersensibilité allergique où une matrice monolithique, par exemple un disque de papier cellulosique ou un bâton à ailettes multiples, est enduite de deux ou de plusieurs allergènes différents provenant de différents groupes d'allergènes.Allergosorbent screening device allowing qualitative titration of human sera for allergic hypersensitivity where a monolithic matrix, for example a cellulosic paper disc or a multi-finned stick, is coated with two or more different allergens from different groups of allergens .

Description

MULTIPLE ALLERGEN-BEARING MATRIXES USEFUL FOR QUALITATIVE ALLERGY SCREENING

FIELD OF THE INVENTION This invention relates to allergen-bearing matrixes or supports, useful for qualitatively screening human sera, by means of the RAST test or modifications thereof, for allergic or atopic hypersensitivity.

BACKGROUND OF THE INVENTION In the mid 1960's, immunoglobulin E (IgE) was isolated and identified as the blood serum component (reagin) that causes allergic or atopic hypersensitivity. The routine adaptation of known radioimmunoassay (RIA) procedures to provide an in vitro test for total IgE and an in vitro RAST

(radioallergosorbent test) assay for the detection of allergen-specific IgE in serum samples, to replace the more cumbersome and uncomfortable skin scratch tests, promptly ensued. Subsequently, known enzyme-labeled immunosorbent

(EIA) and fluorescent immunoassay procedures were also routinely adapted to provide in vitro tests for total IgE and allergen-specific IgE.

The allergosorbent used in such RAST or modified RAST assays generally has been prepared by binding an antigenic substance, or allergen — for example a grass allergen from Bermuda or timothy grass, a weed allergen from common ragweed or Russian thistle, a tree allergen from maple or birch trees, a food allergen from milk or chocolate, an allergen from house dust, dust mites, cat epithelium, dog dander or penicillium notatum, to mention only some of the more common examples — to a solid support, usually a paper disc. The assay is run by taking a small sample of blood from a patient suspected of having allergic hypersensitivity because of such symptoms as rhinitis, itchy or watery eyes, asthma, eczema, hives or localized swelling, correlated in some cases tq particular times of year or particular episodes involving contact with known allergens, and incubating the blood serum with, the allergosorbent to enable allergen-specific IgE from the serum to bind to the allergen on the substrate. Following this incubation, the serum and all non-specific (unbound) IgE present are washed from the substrate, and a labeled anti-IgE is added which binds to the patient's IgE bound to the allergen on the substrate. The quantity of labeled anti-IgE which binds to the patient's IgE determines the patient's sensitivity to that particular allergen. The test is then repeated for each suspected allergen.

The reliability, specificity, sensitivity and ease of performance of the typical battery of RAST tests for initial allergy diagnosis, the convenience this in vitro test method affords the patient, and the obviation, by its use, of unnecessary treatment of patients with false-positive skin responses, are all somewhat offset by the expense involved. In fact in some cases using a RAST test to screen each of the many potentially reactive allergens for each patient can be prohibitively expensive. For this reason, a number of methods have been suggested to permit the use of the RAST test for initial allergy screening at a lower than customary cost.

Each of these methods involves the use of a screen that in one way or another reduces the number of individual RAST tests required, thus reducing the cost to the patient. The screen essentially "weeds out" those patients who are non-allergic with respect to IgE mediated allergies, thereby avoiding the need to perform many more tests on them. Such a screen should detect those patients who are allergic or atopic, and individual RAST tests will then be run on them to determine the particular allergens causing the problem.

Merrett et al. Clinical Allergy, 8, 235-240 (1978) suggested that atopic persons in the United Kingdom can be identified as having circulating IgE antibodies specific for Dermatophagoides pteronyssinus (dust mites), grass pollen and cat dander allergens. Consequently, the authors prepared and tested a "RAST atropy screen" made up of extracts of D. pteronyssinus, meadow fescue pollen and cat dander particles individually coupled to cyanogen bromide-activated microcrystalline cellulose particles and then combined in a particle suspension. The test sensitivity was said to be 97%, and the specificity 100%, when compared to Phadebas RAST analyses run using the individual allergen-containing particles.

A somewhat similar screen has been described by Ownby et al in an abstract entitled "A Comparison of Screening Tests for Childhood Inhalant Allergy" submitted to the American Academy of Allergy and Immunology no later than October 29, 1982. Extracts of ragweed, timothy grass and mite allergens were individually coupled to microcrystalline cellulose particles, and the thus-coupled allergens were then combined to give a single screen. The authors indicate that good agreement was obtained between this screen, RAST assays run using the individual allergens, and skin tests again using the individual allergens. King, Arch Otolaryngol, 108, 781-786 (1982) suggested the "(i)nitial use of a 'screening' RAST that utilizes approximately one third of the allergens in the usual full RAST battery " (at page 781, middle column, last paragraph) . The screening RAST batteries disclosed by King employed 6-10 individual allergen-impregnated paper discs, each individually impregnated with an allergen indicator for major allergen fields (i.e., one weed, one grass, one tree, one mold, one animal epithelium allergen, etc.). The author reported that this mini-RAST battery proved to be 96-99+% efficient, depending on where the cut-off for a true positive response is placed [i.e., F/N (Fadal/Nalebuff) class 1 or 2] .

Nalebuff, Aid Service Corporation Consultants' Report, November, 1982, suggests a "mini screen profile" of six allergens for initial allergy diagnosis: "one grass, one weed, one mold, one animal dander, one tree and dust mite", with the suspected atopic patient's serum being subjected to these allergens in six individual RAST tests. And, in a paper presented at a public Section meeting of the Triological Society at Pebble Beach, California on January 8, 1983, Dr. Nalebuff indicated that such a mini screen profile, using five allergens, has a sensitivity level of 98%.

Archer, in a paper prepared for presentation at the XI International Congress of Allergy and Clinical Immunology, London, England, October 17-23, 1982, described binding groups of related allergens (i.e., a group of grass allergens or a group of weed allergens) to a paper disc for use in initial allergy screening. In May, 1983, Pharmacia Diagnostics commercialized in the United States screens in which individual groups of related allergens, e.g., grass, tree or weed pollens, epidermals, house dust and house dust mites, or molds, are bound to individual paper discs.

U.S. Patent No. 3,720,760 issued March 13, 1973 to Bennich et al, discloses that "a mixture of two or more allergens" may be bonded to a polymeric support and used to test patient sera for allergic hypersensitivity; see column 4, lines 56-64. Nowhere in the Bennich et al patent, however, is it explicitly disclosed that different allergens from different allergen groups may be bonded to the polymeric support.

U.S. Patent No. 3,941,876, issued March 2, 1976, and U.S. Patent No. 4,031,197, issued June 21, 1977, both to Marinkovich, each disclose "...bonding a plurality of separate allergens to an elongated porous support body to form a series of narrow bands of bonded allergen separated by narrow bands of allergen-free support..."; see, for example, U.S. 3,941,876 at column 1, lines 48-51. The Marinkovich patents disclose that the allergen bonded support can then be used in conventional fashion to assay patient serum for allergic hypersensitivity.

Each of the Marinkovich patents uses expressions such as "a large number of allergens", "a plurality of separate allergens", "various allergenic materials", "specific identified allergen", "separate identified allergen", "the allergens to which a patient is hypersensitive", "separate identified allergens" and "a different allergen"; see, for example, column 1, lines 46 and 48-49; column 2, lines 10 and 55; column 3, line 11; column 5, lines 23-24 and column 6, lines 15-16, respectively, of U.S. 3,941,876, and column 2, line 7 of U.S. 4,031,197. Once again, however, neither of these patents explicitly discloses that different allergens from different allergen groups are bonded to the particular supports shown.

U.S. Patent No. 4,327,073, issued April 27, 1983 to Huang, discloses an analytical method for quantitatively analyzing bodily fluids for a plurality of substances, each of which undergoes at least one reaction with a cognate compound. Huang specifically teaches, at from column 10, line 54 to column 11, line 2, using a substrate carrier bearing "immobilized antibodies which conjugate with antigens of unknown quantities in the biological fluid" to analyze an immune system for the antibodies. No specific mention is made of allergens being bound to the immobilized antibodies, nor is there, once again, any disclosure by Huang that a plurality of different allergens from different allergen groups can be bound to the substrate carrier.

DETAILED DESCRIPTION OF THE INVENTION

I have now discovered that allergen-bearing (allergosorbent) screening devices can be prepared which are useful for screening human sera qualitatively, by means of the RAST test or modifications thereof, for allergic hypersensitivity to the entire range of known prevalent allergens responsible for IgE mediated allergies, i.e., to allergens represented by allergen indicators for major allergen fields across the known spectrum of allergens now employed in a full battery of individual RAST tests for IgE mediated allergies. These screening devices comprise a monolithic matrix or support coated with allergens from a plurality of different allergen groups, e.g., weeds, grasses, trees, molds, animal epithelia or dander, dust, dust mites, etc. The monolithic matrixes or supports which can be used in preparing the allergosorbents of the present invention can be any monolithic water-insoluble organic or inorganic matrix or support having surface properties which render it suitable to the adsorption of allergens.

A multifinned stick or similar device of the type disclosed in U.S. Patents Nos. 4,197,278 and 4,225,575, issued April 8 and September 30, 1980, respectively, to Piasio et al, preferably one made of a thermoplastic polymer such as polystyrene, polyethylene, polypropylene, polyvinyl chloride, and the like, can be used, and can be coated with a mixture of all the different allergens making up the screen. Also, if desired, each of the fins in such a stick, e.g., a stick having six or nine fins, can be coated with different allergens entirely or partly from different allergen groups. For example, six allergen screens can be prepared by coating each fin of a six finned molded polystyrene stick with a different allergen, such as one allergen from each of the following sets of six allergens:

Screen No. 1

Alternaria tenuis White oak Short ragweed Dust mite Cat epithelium Rye grass

Screen No. 2

Bermuda grass Dog dander Cladosporioides Mountain cedar American elm False ragweed

Similarly, a nine allergen screen can be prepared by coating each fin of a nine finned molded polyethylene stick with one of the following nine allergens: Screen NO. 3

Dog dander

Timothy grass

June grass (Kentucky Blue)

Birch tree

Dust mite

Short ragweed

Cat epithelium

White oak

Alternaria tenuis

Such multifinned sticks can be molded or otherwise formed as a unitary construction, i.e., with the chosen number of fins initially attached to the stick or shaft. If it is desired to coat each fin in such a stick with a different allergen from different allergen groups, this can be accomplished by dipping each fin into a different liquid allergen extract, painting a different allergen onto each fin, or by any other suitable means.

The central stick or shaft can also be constructed, if desired, to contain a multiplicity of receptacles (slots, holes or the like), or adapted to contain or receive any other suitable fastening means, to accommodate the attachment thereto of any chosen number of fins coated with different allergens from different allergen groups. A batch of fins can be coated with the same allergen, another batch with another allergen from a different allergen group, and so on until the desired number of batches of fins coated with different allergens from different allergen groups has been prepared. Then, the thus-coated batches of fins can be shipped, together with sticks or shafts adapted to receive them, to the allergists, otolaryngologists or general practicioners (or their laboratory technicians) who will connect a desired number of fins bearing different allergens from different allergen groups to a stick and use it as an allergen screen. In this way, different allergen screens containing any chosen number of different allergens, including ones prevalent in particular sections of this or any other country, or ones to which particular populations of patients, e.g., children, are particularly susceptible, can easily be assembled.

Test tubes, beads, sheets, fibers, mats, microtiter plate wells, and the like, made from glass or a thermoplastic polymeric material, can also be used as the monolithic matrix or support, as can monolithic cellulosic substrates such as paper discs or strips.

Among the allergens that can be bonded to the monolithic matrix or support are allergens from the following groups: I. Inhalant Allergens

1. Grasses

Sweet vernal

Bermuda

Orchard (Cocksfoot)

Meadow fescue

Perennial rye

Timothy

Common reed

June (Kentucky blue)

Red top

Johnson

Brome

Cultivated rye

Velvet

Cultivated oat pollen

Cultivated wheat pollen

Meadow foxtail

Bahia

2. Weeds

Common ragweed Western ragweed Giant ragweed False ragweed Wormwood Mugwort Ox-eye daisy Dandelion

English plantain

Lamb's quarter

Russian thistle

Goldenrod

Pigweed

Scale

Marshelder

Firebush (Kochia)

Dock

3. Trees

Maple (box elder)

Alder

Birch

Hazel nut

Beech

Mountain cedar

Oak

Elm

Olive

Walnut

Sycamore

Willow

Cottonwood

White Ash

White pine

Pecan

Mesquite

4. Epidermals

Cat epithelium

Horse dander

Cow dander

Dog dander

Guinea pig epithelium

Pigeon droppings

5. Molds

Penicillium notatum

Cladosporium

Aspergillus fumigatus

Mucor racemosus

Candida

Alternaria

6. House dust

Greer Hollister-Stier

7. Dust mites

D.pternonyssinus D.farinae II. Food Allergens

Egg white

Milk

Codfish

Wheat

Rye

Barley

Oat

Corn

Rice

Pea

Peanut

Soybean

Hazel nut

Brazil nut

Almond

Crab

Shrimp

Tomato

Pork

Orange

Potato

Coconut

Chocolate

Beef

Baker's yeast

Brewer's yeast

Chicken

Tea

Coffee

Lettuce

Lamb

Ordinarily, at least six different allergens, each from a different allergen group, will be employed to coat the monolithic matrix or support when practicing the present invention, although lesser numbers of different allergens from different allergen groups can be employed, if desired (for example, if for any reason the practitioner considers it preferable to use two or more screens, each bearing two or more different allergens from different allergen groups, to carry out a series of screens on patient's sera). As many as 12 to 18 or more allergens from different groups can be used, with each of them being a different allergen from a different allergen group or, as illustrated above by Screen No. 3, with two or more different allergens from some or all of the different allergen groups represented being includable, e.g., two grasses, two trees, two animal epithelia, etc. In fact, the number of allergens includable is limited only by the purity of the allergen extracts employed and the surface area and properties of the monolithic matrix or support.

The allergens used in preparing the present invention's multiallergen screens are chosen, as indicated above, to represent the typical allergens to which a patient population manifesting the symptoms of allergic hypersensitivity is likely to be sensitive, e.g., those IgE mediated allergens in a particular geographic area to which significant numbers of allergic patients are sensitive, those to which children more commonly exhibit sensitivities, foods which frequently cause allergic reactions, etc.

The present invention's multiallergen screens permit an examining physician, oftentimes a general practitioner or an internist in the first instance, to obtain at least an initial indication of allergic hypersensitivity. This is valuable not only when the patient exhibits some or all of the common symptoms of allergies, and the results obtained using the screen will be used by a specialist in allergies to whom the patient will be referred as the basis on which to structure a battery of individual RAST tests, but also when the patient's reported symptoms and history, and the physician's physical examination, do not indicate a typical allergic patient. In such a case, the present invention's multiallergen screen either will rule out one more possibility, or perhaps find the hitherto hidden cause of the patient's complaint. Various procedures can be used to coat the individual allergens onto the monolithic matrix or support. These procedures are, in general, well known in the art, inasmuch as they are, for the most part, the same procedures heretofore used to coat individual substrates with individual allergens.

Thus, for example, procedures such as those set forth in the article by Parsons which appears in Langone et al, Eds., "Methods in Enzymology", Vol. 73, "Immunochemical Techniques", Part B (New York: Academic Press, 1981) at pages 224-239 can be used when the matrix or support is a plastic finned stick, tube or the like.

Similarly, when the matrix or support is a monolithic cellulosic support, such as a paper disc, the following procedure, published by Ventrex Laboratories, Inc. for use in its Neuter Disc Program (by which individual customers are enabled to coat discs with allergen extracts of their own choosing, including extracts which may be commercially unavailable or difficult to obtain) can be used.

This procedure as given here allows 200 discs to be coated at one time. Adjustment of the volumes of reagents employed permits the coating of greater or lesser numbers of discs. The procedure involves first presaturating the discs [typically APT (aminophenylthioether derivative) paper discs (Schleicher & Schuell, Inc., Keene, N.H.) having a diameter of approximately 6.12 mm, a weight/10 discs of 0.0269 gram and a basis weight of 92 grams/square meter] with 20 ml. of cold (4°C) IN HCl. Upon the addition of the 20 ml. of HCl to the disc bottle, the discs and aqueous HCl are swirled for approximately 30-60 seconds, using the disc bottle as a reaction vessel. The disc bottle is then aspirated thoroughly. Next, 20 ml. of cold IN HCl are again added to the disc bottle and swirled. While swirling is continued, 0.6 ml. of a freshly prepared aqueous sodium nitrite solution (1 gram % w/v NaNO₂ in water) is added to the disc bottle, which then contains 200 discs, 20 ml. of cold IN HCl and 0.6 ml. of the aqueous sodium nitrite solution. Swirling of this combination is continued at 2-8°C for 30 minutes. If the swirling is carried out by hand, it should be done for five minutes initially and then once every five minutes thereafter for the full 30 minutes. Preferably, a flask swirling unit will be employed. After the full 30 minutes, the solution is aspirated from the disc bottle. The treated discs are then washed with 10 ml. of cold distilled water, aspirated, and washed again four times in the same manner, making sure that the disc bottle has been aspirated thoroughly after the final wash.

The discs are now ready to coat with the desired allergen extract (extracts containing phenol should not be used). Typical extract dilutions are as follows:

1. For a 1:2 dilution, 10 ml. of the extract are measured and added to discs suspended in 10 ml. of aqueous 0.1M phosphate buffer.

2. For a 1:4 dilution, 5 ml. of the extract are measured and brought up to 10 ml. with aqueous 0.1M phosphate buffer. This is then added to discs suspended in 10 ml. of aqueous 0.05M phosphate buffer, pH=7.5.

3. For any other dilution, the desired amount of extract is measured and added to an equal amount of aqueous 0.1M phosphate buffer, then brought up to 10 ml. with aqueous 0.05M phosphate buffer. After the extract is diluted, the discs are suspended in the correct volume of diluted extract and 10 ml. of aqueous 0.05M phosphate buffer. The combination is then swirled at 2-8°C for one hour, using the same instructions as stated above if swirling is carried out by hand. After one hour, the solution is aspirated and washed with 10 ml. of cold distilled water. This washing procedure is then repeated four times, with the discs being aspirated thoroughly after the final washing step.

Twenty ml. of an aqueous β-naphthol solution (prepared by adding 1 gram percent of β-naphthol, w/v, to water, treating with an aqueous solution containing 10 grams of potassium hydroxide per liter until no β- naphthol flakes are visible, and then back-titrating with aqueous 6N HCl to a slightly acidic pH, about 6, at which point a precipitate should just begin to form) are added to the disc bottle and swirled for 20 minutes at room temperature (about 25°C) . Next, the solution is aspirated off, the discs are washed with 10 ml. of distilled water, aspirated, and this washing step repeated three times, making sure again that the disc bottle has been aspirated thoroughly after the final wash.

The discs are then soaked for 10 minutes in 10 ml. of storage buffer (an aqueous 0.05M sodium phosphate solution containing 0.1 gram percent sodium azide, 0.9 gram percent sodium chloride and 0.1 volume percent Tween 20 nonionic detergent, pH=7.4) in the disc bottle, then aspirated. Ten ml. of the storage buffer are added again to the disc bottle, and the bottle is capped and stored at 2-8 °C.

In this procedure, reacting, the APT paper disc with nitrous acid (HONO, generated by combining hydro chloric acid and sodium nitrite) gives a diazonium salt to which the allergen, a protein, can be covalently bound:

Once all the available protein (allergen) has been bound, the remaining active diazonium sites on the disc are terminated by β-naphthol:

The binding of the allergen to the diazonium salt site on the disc is a coupling reaction, in which nitrogen is retained in the product, rather than a replacement reaction, in which nitrogen is lost as N₂ and some other group becomes attached to the phenyl ring in place of nitrogen:

wherein G must be a strongly electron-releasing group, such as hydroxyl, amino, monoalkylamino or dialkylamino.

The allergens coated on a monolithic support or matrix prepared according to the present invention can be coated onto said support as a mixture of allergens. Thus, equal volumes of each allergen extract employed, each of which extracts can contain, for example, from about 1 ng to about 10 μg, and preferably from about 1 ng to about 5 μg, of allergen per milliliter, in a liquid medium such as distilled water plus 0.4% phenol as a preservative, distilled water plus 50 volume percent glycerine, glycerine plus sodium bicarbonate buffer, or the like, can simply be mixed together at room temperature, then admixed with phosphate buffer, or the like, to a dilution of from about 1:2 to about 1:32, and preferably from about 1:4 to about 1:8. The thus-obtained diluted allergen extract mixture is then coated on the monolithic matrix by any suitable procedure, such as those mentioned above.

The allergosorbents of the present invention can be used in conjunction with the published standard Modified RAST Procedure of Fadal et al, "IgE in Investigation and Management of Atopic Disorders; Recent Advances", J.Cont.Ed. in O.R.L. and Allergy, 40, 47-59 (1978), which can be summarized as follows:

1. A blood sample is collected by venipuncture and the serum is separated by centrifugation. The serum should be stored at 2-8°C until assayed, and repeated freezing and thawing of the serum should be avoided.

2. Time Control: A 1:4 dilution of the 100 U/ml IgE standard in a total IgE kit is prepared using 0.9% saline. The resulting 25 U/ml IgE sample can then be used as the time control for the multiallergen RAST screens of the present invention. Alternatively, no time control need be run if, as is usually the case with the multiallergen screens of the present invention, a simple yes/no qualitative response will suffice.

3. Positive Control: Serum is pooled from patients sensitive to one particular allergen (e.g., ragweed). When tested against the appropriate homologous RAST allergen disc, the positive control serum should give binding comparable to that obtained using time control, if one is used.

4. Negative Control: One or more of the following can be used:

(a) pooled fresh human cord serum, (b) pooled serum samples (3-5) from non- atopic individuals with total IgE of less than 10 U/ml, with negative RAST scores and/or skin test results, (c) serum from an atopic individual (e.g., test such serum against an allergen disc to which patient is negative).

5. The tubes are labeled and arranged as shown in Table II below.

6. One IgE disc is added to tubes #3, 4.

7. Appropriate RAST allergen discs are added to tubes #5, 6 and #7, 8 respectively.

8. One test RAST allergen disc (as requested) is added to tube #9, etc.

9. 100 μl of 25 U/ml total IgE is pipetted into tubes #3 and #4.

10. 100 μl of positive control is pipetted into tubes #5 and #6.

11. 100 μl of negative control (cord serum or pooled normal human serum) is pipetted into tubes #7 and #8.

12. 100 μl of unknown patient's sera is pipetted onto RAST disc in tubes #9, etc.

13. The tubes are then covered with aluminum foil or plastic film after all the serum has been pipetted, and let the covered tubes stand at room temperature (about 25 °C) overnight (16-24 hours).

14. 2.5 ml of 0.9% saline is added to tubes #3 onward and allowed to stand for 10 minutes.

15. The saline is removed completely; the rinsing procedure in step 14 is repeated two more times .

16. 50 1 of Anti-IgE¹²⁵I is pipetted into the bottom of all tubes from #1 upwards.

17. Tubes #1 and #2 are capped, all tubes are covered with aluminum foil or plastic film and allow to stand at room temperature overnight. 18. The washing procedure outlined in step #14 is repeated 3 times.

19. The discs are transferred to clean tubes with corresponding labeled numbers.

20. In a gamma counter, tube #3 is counted until the counter registers 25,000 counts. The amount of time required is recorded. The same procedure is repeated for tube #4. The average time to reach 25,000 for tubes #3 and #4 is calculated and recorded. (See example under Table II) .

21. The radioactivity in tubes 1, 2, 5, 6, 7, etc. is counted for the average time calculated in step 20 above, and the counts for all tubes are recorded.

Note: Negative control tubes #7, 8 should count to 500 counts ± 200 counts.

22. The patient's test results are expressed as counts or as % time control, and the results can be classified according to the breakdown given in Table I below:

The allergosorbents of the present invention can also be used in other recognized RAST procedures, e.g., ones involving the use of radioactive tags other than 1²⁵I to label the anti-IgE, such as ¹³¹I, ³H, ¹⁴C or any other conveniently measurable radioisotope, or ones involving anti-IgE tagged with an enzyme, such as horseradish peroxidase or β-galactosidase, or with a fluorogenic, chromophoric or luminescent tag.

In order that those skilled in the art can more fully understand the present invention, the following examples are set forth. These examples are given solely for purposes of illustrating the invention, and should not be considered as expressing limitations unless so set forth in the appended claims. All parts and percentages are by weight, unless otherwise stated.

Example I Two ml. of extracts of each of the allergens identified hereinabove as being present in Screen No. 1, i.e., A. tenuis, white oak, short ragweed, dust mite, cat epithelium (Meridian: lot nos. 3D15; 1T13; 3C14; 2F22 and 2K28, respectively) and rye grass (Hollister-Stier: Code No. 4042) , in water/glycerine medium, were admixed at room temperature (about 25°C) and then diluted 1:4 with aqueous 0.05M phosphate buffer, pH=7.4.

Teh ml. of cold (4°C) 1N hydrochloric acid were added to 100 APT (aminophenylthioether derivative) cellulosic paper discs (obtained from Schleicher & Schuell, Inc., Keene, N.H. and weighing a total of 0.28 gram), contained in a suitable vessel. The aqueous hydrochloric acid-disc mixture was swirled, then decanted, and 10 ml. more of cold 1N hydrochloric acid were added, followed by 300 μl. of a mg./ml. dilution of sodium nitrite prepared by adding 0.020 grams of sodium nitrite to 2 ml. of distilled water. The vessel containing the discs, the aqueous hydrochloric acid and the aqueous sodium nitrite solution was placed on a shaker-in-the-round in a walk-in cooler, shaken for 30 minutes, and the discs were then aspirated and washed 4 times with cold distilled water, with aspiration after each washing.

2.5 ml. of the above-prepared six allergen-containing extract, were added to 2.5 ml. of 0.1M phosphate buffer. Then, 5 ml. of 0.05M phosphate buffer were added to the vessel containing the washed, aspirated discs, followed by the 5 ml. of the six allergen-containing extract in 0.1M phosphate buffer, with the vessel being swirled gently as the extract was added. The vessel was then placed on the shaker-in-the-round in the walk-in cooler and shaken for one hour.

Next, the discs were aspirated and washed 4 times with cold distilled water, with aspiration after each washing. Then, 10 ml. of an aqueous β-naphthol solution, prepared by adding 1 gram of β-naphthol to 100 ml. of distilled water, then adding 10-12 potassium hydroxide pellets to aid in dissolving the β-naphthol, and then back-titrating the resulting solution to a pH of approximately 6.0 with 6 N hydrochloric acid, were added to the washed discs and shaking continued for 15 minutes. Following this reaction the discs were aspirated and washed 3 times with distilled water, with aspiration after each washing.

Finally, 10 ml. of the storage buffer described hereinabove (an aqueous 0.05M sodium phosphate solution containing sodium azide, sodium chloride and Tween 20 nonionic detergent, pH=7.4) were added to the vessel containing the discs, let stand for ten minutes, and then aspirated. After adding 10 ml. more of the storage buffer, the discs were labeled and stored at 2-8°C.

Example II The procedure of Example I was repeated in every respect but one, namely, 2 ml of extracts of each of the allergens identified hereinabove as being present in Screen No. 2, i.e., Bermuda grass, Cladosporioides, mountain cedar, American elm (Meridian: lot nos. 3A21, 2E2, 1L9 and 2K24, respectively), dog dander (Hollister- Stier: Code No. 4084) and false ragweed (Greer: Code No. 185), in a water-glycerine medium, were substituted for the allergen extracts used in Example I.

Example III The procedure of Example I was again repeated in every respect but one, namely, 2 ml of extracts of each of the allergens identified hereinabove as being present in Screen No. 3, i.e., dog dander, June grass (Kentucky blue), cat epithelium (Hollister-Stier: Code Nos. 4084, 1190 and 4042, respectively), birch tree, dust mite, short ragweed, white oak, A. tenuis (Meridian: lot nos. 0G3B, 2F22, 2K1, 1T13 and 3D15, respectively) and timothy grass (Greer: Code No. 28) , in a water-glycerine medium, were substituted for the allergen extracts used in Example I.

Example IV The screen discs prepared as described in Examples I-III above were evaluated by using them to assay sera from 21 patients in side-by-side comparison with individual allergen-bearing cellulose paper discs. The standard Fadal/Nalebuff Modified RAST assay procedure described above was used in this evaluation, and the scoring was done using the Fadal/ Nalebuff Modified RAST scoring system shown in Table I above. Table III below records the results obtained in this evaluation using Screens Nos. 1, 2 and 3 and individual discs, both by Fadal/Nalebuff class and by individual counts bound in each test.

(a) Two false negative results were obtained on this individual with Screen Nos. 1 and.3, since when the patient' s serum was run using individual discs whose allergens were represented in these screens, a positive result (Class III) was obtained on A. tenuis each time. The capacity of the monolithic matrix employed, a cellulose paper disc about 6 mm in diameter, is limited by its surface area. When using matrixes whose capacities are limited, it may be necessary to standardize or otherwise manipulate the allergen extract employed. For example, it may be necessary to purify extracts known to have very low potency before coating the matrix with them to insure that the coated matrix screen will pick up any IgE antibody in the patient's serum specific to this allergen.

(b) In each of these cases the screening disc bound significantly more counts than were bound by the individual discs whose allergens were represented in the screens. However, since not all of the allergens represented in the screens were run on individual discs with these patients' sera, it is entirely possible that one or more of the allergens to which these patients are most sensitive were not run on individual discs. It should also be noted that binding on the screening discs could very well proceed cumulatively

Example V

An allergen extract pool for coating cellulosic paper discs, the insides of plastic tubes and plastic multifinned sticks was prepared by mixing 13 ml. of each of the following Meridian allergen extracts, each in a water-50 volume % glycerine medium, in a clean vessel at 2-8°C:

Allergeann Extract Lot No.

G2 Bermuda grass 3A21

G8 June (Ky. blue) grass 2G8 G10 Johnson grass 2K9

W1 Common ragweed 3G18 W9 English plantain 3B26 W22 Pigweed 3D2

T1 Maple/box elder 3F12 T6 Juniper/mountain cedar 3E26 T7 Oak 1113

T8 Elm 2K24

E1 Cat epithelium 3J25 E2 Dog dander 3A1

M2 Cladosporium 3C8 M6 Alternaria 3F20

D2 D.farinae (dust mite) 3F16

Once mixed, the allergen extract pool was covered, labeled and stored at 2-8°C.

Five packets of 1000 APT (aminophenylthioether derivative) cellulosic paper discs (Schleicher & Schuell) each were emptied into a 1 liter round bottom flask, 500 ml. of cold (4°C) 1 N hydrochloric acid were added and swirled. The aqueous hydrochloric acid was then aspirated, and 50.0 ml. more added, followed by 15 ml. of a 10 mg./ml. aqueous solution of sodium nitrite. The flask was then placed in a shaker in a walk-in cooler and shaken for 30 minutes, following which the discs were aspirated, then washed 4 times with cold distilled water, with aspiration after each washing.

A 1:2 dilution of the above-prepared 15-allergen extract pool was prepared by adding 125 ml. of the pool to 125 ml. of 0.1M phosphate buffer. This 1:2 dilution was then added to the 5000 discs, which had been suspended in 250 ml. of 0.05M phosphate buffer in the round bottom flask, giving a 1:4 dilution of the mixed allergen pool in contact with the discs. The flask was then shaken in the walk-in cooler for 1 hour, following which the discs were aspirated and washed 4 times with cold distilled water, with aspiration after each washing.

500 ml. of an aqueous 1 gram percent -naphthol solution were then added, and the flask was shaken in the walk-in cooler for 20 minutes. The discs were then aspirated and washed 3 times with distilled water, with aspiration after each washing.

After soaking the discs in 500 ml. of the above-described storage buffer for 10 minutes, aspirating, and then adding 500 ml. more of the storage buffer, the discs were transferred, with the storage buffer, to a storage vessel, labeled, and kept at 2-8°C.

Example VI

An allergen extract pool for coating cellulosic paper discs, the insides of plastic tubes and plastic multifinned sticks was prepared by mixing 2 ml. of each of the following twenty-four allergen extracts in a clean vessel at 2-8°C: Allergen Source and Extract Lot No.

Timothy grass Greer - 28 Bermuda grass Meridian - 1K11B June (Ky. blue) grass Meridian - 2G8

Maple/box elder Hollister-Stier - 1211 White oak Hollister-Stier - 2033 Birch tree Meridian - 0G3B Mountain cedar Meridian - 1L9 Mesquite Meridian - 2J16

Cat epithelium Hollister-Stier - 4042 Dog dander Hbllister-Stier - 4084 Horse dander Hollister-Stier - 4426 Dust mite Meridian - 2F22

Common (short) ragweed Meridian - 3A4 Western ragweed Meridian - 2E4 English plantain Meridian - 1L13 Lamb's quarters Meridian - 3A18 Sage (common mugwart) Meridian - 2F2

A. tenuis Hollister-Stier - 5009

Cladosporium herbarum Meridian - 3A8 Aspergillus fumigatus Meridian - 2H23 Penicillium notatum Meridian - 2H24B

Cow's milk Meridian - 2A3 Egg white Meridian - 3A9 Wheat Hollister-Stier - 3708

Once mixed, this allergen extract pool was covered, labeled and stored at 2-8°C.

Two thousand APT (aminophenylthioether derivative) cellulosic paper discs (Schleicher & Schuell), contained in a 1 liter round bottom flask, were presaturated with 200 ml. of cold (4°C) IN hydrochloric acid by adding the aqueous acid, swirling the flask, and then aspirating the acid. Then, 200 ml. more of cold 1N hydrochloric acid were added, followed by 6 ml. of an aqueous sodium nitrite solution prepared by adding 0.6 gram of sodium nitrite to 6 ml . of distilled water . The flask was then placed in a shaker in a walk-in cooler and shaken for 30 minutes, after which the discs were aspirated, then washed 5 times with cold distilled water, with aspiration after each washing.

Forty-eight ml. of bove-prepared 24 allergen extract pool, 48 ml. of 0.1M phosphate buffer and 4 ml. of 0.05M phosphate buffer were admixed, with stirring. Then 100 ml. of this mixture were added to the above-prepared 2000 diazotized discs suspended in 100 ml. of 0.05M phosphate buffer, while agitating, and the resulting mixture was shaken for 1 hour in the walk-in cooler. The discs were then aspirated and washed 5 times with cold water, with aspiration after each washing.

Two hundred ml. of an aqueous β-naphthol solution (prepared by adding 2.5 grams of β-naphthol to 250 ml. of distilled water, then adding 2.4 grams of potassium hydroxide, and finally back-titrating with 7.5 ml. of 6N hydrochloric acid) were added to the flask containing the discs, and the flask was then shaken in the walk-in cooler for 20 minutes, aspirated, and washed 4 times with cold distilled water, with aspiration after each washing.

After soaking the discs in 125 ml. of the above-described storage buffer for ten minutes, aspirating, and then adding 125 ml. more of the storage buffer, the discs were transferred, with the storage buffer, to a storage bottle, labeled, and stored at 2-8 °C.

It will be obvious to those skilled in the art that other changes can be made in carrying out the present invention without departing from the spirit and scope thereof as defined in the appended claims.

Claims

I claim:

1. An allergosorbent screening device for qualitatively assaying human sera for allergic hypersensitivity which comprises two or more different allergens from different allergen groups coated on a monolithic matrix.

2. An allergosorbent screening device as described in claim 1 wherein at least six different allergens from different allergen groups are coated on said matrix.

3. An allergosorbent screening device as described in claim 1 wherein said matrix is a cellulose paper disc.

4. An allergosorbent screening device as described in claim 3 wherein said allergens are intermingled on the surface of said disc.

5. An allergosorbent screening device as described in claim 1 wherein said matrix is a multifinned stick.

6. An allergosorbent screening device as described in claim 5 wherein each fin of said multifinned stick is coated with an allergen from a different allergen group.

7. An allergosorbent screening device as described in claim 6 wherein said fins are removably attached to said stick.

8. An allergosorbent screening device as described in claim 1 wherein allergens from at least three different allergen groups are coated on said matrix.

9. An allergosorbent screening device as described in claim 8 wherein at least two allergens from at least one of said three different allergen groups are coated on said matrix.

10. An allergosorbent screening device as described in claim 8 wherein said allergens comprise Alternaria tenuis, white oak, short ragweed, dust mite, cat epithelium and rye grass.

11. An allergosorbent screening, device as described in claim 8 wherein said allergens comprise Bermuda grass, dog dander, Cladosporioides, mountain cedar, American elm and false ragweed.

12. An allergosorbent as described in claim 9 wherein said allergens comprise dog dander, timothy grass, June grass, birch tree, dust mite, short ragweed, cat epithelium, white oak and Alternaria tenuis.

13. An allergosorbent screening device as described in claim 5 wherein said allergens are intermingled on the surfaces of the fins of said multifinned stick.